Fun with the Radio
Shack EC4026
(Equivalent of the Casio fx4500P)
Programming Notes
The syntax for prompting for variables and displaying
results are slightly different from the usual Casio programming language (as I
mentioned, the EC4026 is a clone of the fx4500P). Check out the unusual IfThenElseEnd
structure as well.
Prompting Syntax:
{var} : var “prompt
string”
Example:
{X}: X”ENTER X”
Display Syntax:
Calculation
“Display string” ◢ (solid right triangle, [2ndF] [↑])
Example:
X
“F(X)=” ◢
The IfThenElseEnd Structure:
If condition ⇒ do if the condition is true
⇏do if condition is false ◺
(clear right triangle, [2ndF] [√])
Note: I symbolize the [x^y] by ^.
Finding the Monthly Payment of a Mortgage
with Total Interest Paid and Total Cash Outflow
Program MORTGAGE:
L1 Fix 2
L2 {A}: A”LOAN
AMOUNT”
L3 {Y}: Y”YEARS”
L4 {I}: I”RATE”
L5 I = I/1200
L6 N = Y*12
L7 P =
A*(I(1+I)^N)/((1+I)^N1)
L8 “MONTHLY PMT” ◢
L9 N*P
L10 “OUTFLOW” ◢
L11 N*PA
L12 “TOTAL INTEREST”
◢
L13 Norm
Example:
A: Loan is $250,000.00
Y: 30 years
I: Interest rate of
4%
Results:
P: Payment:
$1,193.59
Outflow: $429,673.77
Total
Interest: $179,673.77
Midlength, Height, and Area of a Trapezoid
Program TRAPEZIOD:
L1 {A}
L2 {B}
L3 {C}
L3 {C}
L4 {D}
L5 H =
√((A+B+C+D)*(AB+C+D)*(AB+CD)*(ABC+D))/(2*Abs(BA))
L6 M = (A+B)/2
L7 K = M*H
L8 M
L9 “MIDLENGTH” ◢
L10 H
L11 “HEIGHT” ◢
L12 K
L13 “AREA” ◢
Quadratic Equation
A*x^2 + B*x + C = 0
Program QUAD:
L1 {A}: A”A”
L2 {B}: B”B”
L3 {C}: C”C”
L4 D = B^24*A*C
L5 D<0 ⇒ Goto 1 ◺
L6 X = (B +
√D)/(2A) ◢
L7 Y = (B 
√D)/(2A) ◢
L8 Goto 0
L9 Lbl 1
L10 X = B/(2A)
L11 “REAL” ◢
L12 Y = √(Abs
D)/(2A)
L13 “IMAG” ◢
L14 Lbl 0
L15 “DONE” ◢
Example:
3x^2 + 6x – 1 = 0;
A = 3, B = 6, C = 1
Result: 0.154700538, 2.154700538
3x^2 + 6x + 10 = 0;
A = 3, B = 6, C = 10
Result: REAL: 1, IMAG: 1.527525232. 1 ± 1.527525232i
Minimum Loss Matching
Variables:
Input: Y = Z0, Z =
Z1
Output:
R = R1
S = R2
L = Loss Marching
Program MINLOSS:
L1 1: “Z1<Z0” ◢
L2 {Y}: Y”Z0”
L3 {Z}: Z”Z1”
L4 L = √(1 – Z/Y)
L5 R = Y*L: “R1”◢
L6 S = Z/L: “R2” ◢
L7 L = 20 log
(√(Y/Z) + √(Y/Z – 1)): “LOSS” ◢
Example:
Input:
Y: Z0: 15
Z: Z1: 10
Output:
R1: 8.66025 Ω
R2: 17.32051 Ω
Loss: 5.71948
Add Two Polar Numbers
Polar and
Rectangular conversions
Variable

Rectangular Results

Polar Results

V

x

r

W

y

θ

Program ADDPOLAR:
L1 {R}: R”R1”
L2 {S}: S”ANG1”
L3 Rec(R,S)
L4 R = V: S = W
L5 {V}: V”R2”
L6 {W}: W”ANG2”
L7 Rec(V,W)
L8 R = R+V: S = S+W
L9 Pol(R,S)
L10 V: “R SUM”◢
L11 W: “ANG SUM”◢
Example:
4 ∠
20° + 3 ∠ 11 ° (In Degrees Mode)
Result (rounded to
4 digits): 6.9789 ∠ 16.1442°
How to Handle a Tax Bracket (Simple Sample)
Take a sample (and
simplified) tax bracket, where income is X:
0 < X ≤
200: tax rate is 10% of X
200 < X ≤ 600: tax rate is 13% of X
600 < X: tax rate
is 16% of X
Program:
L1 {X}: X”X”
L2 X > 600 ⇒ P = 16: Goto 1 ◺
L3 X > 200 ⇒ P = 13: Goto 1 ◺
L4 P = 10
L5 Lbl
L6 X * P/100
Eddie
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Shore. Unauthorized use and/or
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